The superconducting properties of oxide superconductors can be greatly influenced by the oxygen content within these oxides. The first oxide superconductor found to possess a critical temperature in excess of the boiling point of liquid nitrogen, 77.degree. K, is YBa.sub.2 Cu.sub.3 O.sub.7-y. The YBa.sub.2 Cu.sub.3 O.sub.7-y compound can possess oxygen contents ranging from about YBa.sub.2 Cu.sub.3 O.sub.6.05 (y.apprxeq.0.95) to about YBa.sub.2 Cu.sub.3 O.sub.6.95 (y.apprxeq.0.05). See R. Bormann, J. Nolting, "Stability Limits of the Perovskite Structure in the Y--Ba--Cu--O System," Applied Physics Letters, Vol. 54, No. 21, pg. 2148 (1989); T. B. Lindemer, J. F. Hunley, J. E. Gates, A. L. Sutton, Jr., J. Brynestad, C. R. Hubbard, P. K. Gallagher, "Experimental and Thermodynamic Study of Nonstoichiometry in &lt;YBa.sub.2 Cu.sub.3 O.sub.7-x &gt;," Journal of the American Ceramic Society., Vol. 72, No. 10, pg. 1775 (1989); and J. D. Jorgensen, M. A. Beno, D. G. Hinks, L. Soderhold, K. J. Volin, R. L. Hitterman, J. D. Grace, I. K. Schuller, C. U. Segre, K. Zhang, M. S. Kleefisch, "Oxygen Ordering and the Orthorhombic-to-Tetragonal Phase Transition in YBa.sub.2 Cu.sub.3 O.sub.7-x," Physical Review B, Vol. 36, No. 7, pg. 3608 (1987). As the oxygen content of YBa.sub.2 Cu.sub.3 O.sub.7-y increases, the critical temperature, T.sub.c, also increases to a point where, at compositions of about YBa.sub.2 Cu.sub.3 O.sub.6.9, T.sub.c .gtoreq.85.degree. K. See W. E. Farneth, R. K. Bordia, E. M. McCarron III, M. K. Crawford, R. B. Flippen, "Influence of Oxygen Stoichiometry on the Structure and Superconducting Transition Temperature of YBa.sub.2 Cu.sub.3 O.sub.x," Solid State Communications, Vol. 66, No. 9, pg. 953 (1988). While Bi--Sr--Ca--Cu--O-bearing and Tl--Ba--Ca--Cu--O-bearing type superconductors possess narrower ranges of oxygen contents, the superconducting properties of these oxides are also dependent on the oxygen concentration.
It is usually desirable to produce a bulk superconductor (e.g., in the form of a wire, tape, pellet, cylinder, thick film, etc.) with a high density (low porosity), so as to maximize the amount of supercurrent that can be carried by the superconductor. Unfortunately, dense, bulk oxide superconductors need to be annealed for prolonged periods of time in contact with an oxygen-bearing media (i.e., any solid, liquid or gas; e.g., pure oxygen or air at ambient pressure) in order to allow for sufficient oxygen diffusion to achieve a desired oxygen content (and hence, a high Tc substantially throughout the bulk of the superconductive oxide).
Partial melt processing (so-called "melt-textured growth" or "top-seeded melt texturing") has yielded bulk forms of YBa.sub.2 Cu.sub.3 O.sub.x with a high degree of crystallographic alignment. See S. Sengupta, J. Corpus, J. R. Gaines, Jr., V. R. Todt, X. Zhang, D. J. Miller, "Fabrication of Large Domain YBa.sub.2 Cu.sub.3 O.sub.x for Magnetic Suspension Applications," Proceedings of the Third International Conference on Magnetic Suspension Technology, Tallahassee, Fla., 1995; V. R. Todt, S. Sengupta, D. J. Miller, "Processing of Single- and Multi-Domain YBa.sub.2 Cu.sub.3 O.sub.x Bulk Materials for Levitation Applications by Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y Seeding," Applied Superconductivity, Vol. 3, No. 1-3, pg. 175 (1995); V. R. Todt, S. Sengupta, D. Shi, P. R. Sahm, P. J. McGinn, R. B. Poeppel, J. R. Hull, "Processing of Large YBa.sub.2 Cu.sub.3 O.sub.x Domains for Levitation Applications by a Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y Seeded Melt-Growth Technique," Journal of Electronic Materials, Vol. 23, No. 11, pg. 1127 (1994); and C. -J. Kim, H.- W. Park, K. -B. Kim, G. -W Hong., "New Method of Producing Fine Y.sub.2 BaCuO.sub.5 in the Melt-Textured Y--Ba--Cu--O System: Attrition Milling of YBa.sub.2 Cu.sub.3 O.sub.x --Y.sub.2 BaCuO.sub.5 Powder and CeO.sub.2 Addition Prior to Melting," Superconductor Science and Technology, Vol. 8, pg. 652 (1995). Such melt-processed YBa.sub.2 Cu.sub.3 O.sub.x has potential use in applications such as bearings, clamps, cryopumps, cryocoolers, cryoflowmeters, energy storage devices (e.g., flywheels), motors, electromagnetic projectiles, vibration isolation, contactless transportation and fault current limiting. See F. C. Moon, Superconducting Levitation, Applications to Bearings and Magnetic Transportation, John Wiley & Sons, Inc., 1993; J. R. Hull, R. B. Poeppel, HTS Materials, Bulk Processing and Bulk Applications, World Scientific, N.J., pg. 484 1992; S. Sengupta, J. Corpus, J. R. Gaines, Jr., V. R. Todt, X. Zhang, D. J. Miller, "Fabrication of Large Domain YBa.sub.2 Cu.sub.3 O.sub.x for Magnetic Suspension Applications," Proceedings of the Third International Conference on Magnetic Suspension Technology, Tallahassee, Fla., 1995; J. Acero, L. Garcia-Tabares, M. Bajko, J. Calero, X. Granados, X. Obradors, S. Pinol, "Current Limiter Based on Melt Processed YBCO Bulk Superconductors," IEEE Transactions on Applied Superconductivity, Vol. 5, No. 2, page 1071 (1995); and R. L. Meng, L. Gao, P. Gaurier-Picard, D. Ramierez, Y. Y. Sun, C. W. Chu, "Growth and Possible Size Limitation of Quality Single-Grain YBa.sub.2 Cu.sub.3 O.sub.x," Physica C, Vol. 232, pg. 337 (1994). In the case of bulk, melt-textured YBa.sub.2 Cu.sub.3 O.sub.7-y, cylinders having dimensions in the general range of 1.1 to 4.5 cm diameter and 0.5 to 1.6 cm thickness, several days or weeks of annealing in air or oxygen at ambient pressure and at temperatures of 400 to 5000 C are often required to achieve a fully oxygenated component. See S. Sengupta, J. Corpus, J. R. Gaines, Jr., V. R. Todt, X. Zhang, D. J. Miller, "Fabrication of Large Domain YBa.sub.2 Cu.sub.3 O.sub.x for Magnetic Suspension Applications," Proceedings of the Third International Conference on Magnetic Suspension Technology, Tallahassee, Fla., 1995; Private Communication, Dr. S. Sengupta, SCI, Jul. 29, 1996; V. R. Todt, S. Sengupta, D. Shi, P. R. Sahm, P. J. McGinn, R. B. Poeppel, J. R. Hull, "Processing of Large YBa.sub.2 Cu.sub.3 O.sub.x Domains for Levitation Applications by a Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y Seeded Melt-Growth Technique," Journal of Electronic Materials, Vol. 23, No 11, pg. 1127 (1994); F. Frangi, E. Varesi, G. Ripamonti, S. Zannella, "Enhanced Levitation Properties in Melt-Textured YBCO Samples Growth Without Temperature Gradient," Physica C, Vol. 233, pg. 301 (1994); R. L. Meng, L. Gao, P. Gautier-Ociard, D. Ramnierez, Y. Y. Sun, C. W. Chu, "Growth and Possible Size Limitation of Quality Single-Grain YBa.sub.2 Cu.sub.3 O.sub.x " Physica C, Vol. 232, pg. 337 (1994); and K. Sawano, M. Morita, M. Tanaka, T. Sasaki, J K. Kimura, S. Takebayashi, M. Kimura, K. Miyamoto, Japanese Journal of Applied Physics, Vol. 30, pg. L1157 (1991). For example, Todt et al. annealed oxygenated melt-textured pellets of dimensions 1.1 to 2.3 cm diameter by 0.8 to 1.6 cm thick for 10 days at 450.degree. C. See V. R. Todt, S. Sengupta, D. Shi, P. R. Sahm, P. J. McGinn, R. B. Poeppel, J. R. Hull, "Processing of Large YBa.sub.2 Cu.sub.3 O.sub.x Domains for Levitation Applications by a Nd.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y Seeded Melt-Growth Technique," Journal of Electronic Materials, Vol. 23, No. 11, pg. 1127 (1994). Meng et al. oxygenated 2.5 cm diameter by 1 cm thick cylinders of melt-textured YBa.sub.2 Cu.sub.3 O.sub.7-y at 500.degree. C. in flowing oxygen for 150 to 300 hours (about 6 to 12 days). See R. L. Meng, L. Gao, P. Gautier-Picard, D. Ramierz, Y. Y. Sun, C. W. Chu, "Growth and Possible Size Limitation of Quality Single-Grain YBa.sub.2 Cu.sub.3 O.sub.x," Physica C, vol. 232, pg. 337 (1994). Such long annealing times are unattractive for large-scale manufacturing.
Accordingly, it is desirable to develop processes by which oxide superconductors can be oxygenated in an efficient manner, and with an economic application of energy.